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P3-P POTENTIALLY DISASTROUS FLIGHT MALFUNCTION

Discussion in 'Pro/Adv Discussion' started by phantom1972, Nov 13, 2015.

  1. phantom1972

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    I wasn't sure what to title this thread, or what to search on to see if anyone else has had it occur. I saw a "hazardous maneuver" thread, and this might fall into that category, for some unknown reason. My "turning technique" will be considered as such by me for a while. "Dangerous" from "Ridiculous". LOL

    I was flying up the beach, with full forward right stick (pitch), and at maximum speed. I don't remember the wind direction. I decided to head back, and I'll admit to a rather absurd 180 degree turning method. Barely any left bank, and full left "rudder", until my heading was back the way I was traveling, and then I neutralized everything but the full forward pitch. So basically I slid the P3P around 180 degrees rather abruptly while traveling at maximum speed. I can see as this might confuse the accelerometer interaction with the compass and GPS. It apparently did, and it got STUCK in the "confused state". GET THIS: AFTER ROTATING MY HEADING 180 DEGREES, THE P3P KEPT GOING IN THE SAME DIRECTION, BACKWARDS! That got my attention very quickly.

    I was rather astonished, and naturally went to neutral and now I'm going to ruin this story as far as providing useful trouble shooting. Before I could evaluate the effectiveness of different control inputs, I backed into my self imposed 500m geo-fence, and stopped. Just before, I had of course neutralized the forward pitch. And I stopped, but nearly simultaneously got the "distance limit reached prompt."

    As I was kind of concerned, I didn't do the obvious experiment -- pull the pitch control backwards and see if it went forward away from my geo-fence limit back towards me. I just saw that after neutralizing, it was just sitting there, and full forward didn't move me forward. At this point, I hit RTH, and whatever state I got the bird into apparently was cleared out, and it started to head on back to me. After a short time I cancelled the return to home, and everything worked fine. To me, the moral of the story is that I had somehow got my quad into an abnormal state from which it couldn't escape, and DJI luckily designed their RTH function to clear out whatever was stuck. "Experimenting" with stick inputs would have been interesting, but RTH was the correct response.

    DOES ANYONE HAVE ANY IDEAS, COMMENTS (No, I won't turn this way again) OR SIMILAR EXPERIENCE? An abrupt turn that is nearly all a skid is ridiculous thing to do. In an airplane it would be all rudder and it wouldn't turn fast -- for a 180 degree turn it wouldn't enter anyone's mind of a nanosecond. In a helicopter, I'd fear dying. LOL So why I turned this abruptly with no coordinated controls is a mystery too me. But given there is no "turn coordinator" so you can see if you are making a coordinated turn (i.e. One in which the forces remain perpendicular to the air-frame. So you could drink from a glass of water during a steeply banked turn in a plane. Even in a barrel roll!) you won't be perfectly coordinated. But I took it nearly as extreme as you can get, and achieved a rather interesting result, which is a bug, because I don't think a state like this should persist. ???
     
    Hugh-1 likes this.
  2. eBird

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    Interesting. I've done this type of maneuver as well, although probably not at full forward pitch (but pretty close). I often just use yaw to steer the bird, and don't often try to coordinate the turn with right stick banking. Never had it argue with me.
     
  3. olof Ekbergh

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    It almost sounds like you were in IOC mode.

    I do that move all the time with a ll my MRs the P3P is one of them. When I am checking that is is flying OK. I do that move with new ones I help set up for others as well.

    It has never lead to a problem for me. On at least 3 P3Ps. And dozens of other MRs.
     
  4. Meta4

    Meta4 Moderator
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    I've turned my Phantoms inside-out and never observed any issues like this.
    I'd suggest some experimenting to see if you can replicate it.
     
  5. Oso

    Oso

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    I also do that move often, but only in ATTI mode.
     
  6. Wibble

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    Why do you have a 500m limit? There is no need.
     
  7. Ptr

    Ptr

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    You were flying away from yourself

    "I was flying up the beach, with full forward right stick"

    You decided to turn around & towards yourself

    "I decided to head back, and I'll admit to a rather absurd 180 degree turning method"

    So you must have done a 360 degree ???

    "until my heading was back the way I was traveling" which was forward as you said

    360 degrees I'd say you done because you were forward @ this stage

    GET THIS: AFTER ROTATING MY HEADING 180 DEGREES, THE P3P KEPT GOING IN THE SAME DIRECTION, BACKWARDS" ???

    You were obviously going forward because you

    "Before I could evaluate the effectiveness of different control inputs, I backed into my self imposed 500m geo-fence"
    Hello Hello

    Now sir / madam I might be backwards in coming forward but I'm glad you got your bird back your spacial awareness might need calibrating
     
    phantom1972 likes this.
  8. ianwood

    ianwood Taco Wrangler
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    Sounds like a spatial disorientation issue. 0.5km away is not a short distance. It is very easy to get confused as to what's happening. If you have video and data to support what happened, we could revisit it.
     
  9. phantom1972

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    The Ocean makes spacial disorientation pretty difficult. I had the limit set at 500m, because I hadn't had it long, and figured I wouldn't be going any further. I've had it 2+ miles out since. No Problem! 500m is normally too far too see with "unaided vision", but I have eyes like an eagle! Actually I was totally FPV, heading North (Ocean on the right), and abruptly turned back South (Ocean on the left). 180 degrees. And when you're headed South (Ocean on the left), and the stick is full forward, and you are rapidly going backwards, it means your really still going North. It was rather disconcerting. Not really disorienting. I have the video, and have pondered it over many times too.

    I've lived around here for years too, and know the area. The 500 m fence just happened to be set, I hadn't planned on going up the beach that far. I hoped I'd hear answers like these. That it sounds like something fluky. Not having seen anything like it before, and being physically far away, probably made my decision to hit RTH, and hope that would reset any weird internally stored "state" correct. It immediately started flying in the direction it was pointing, and climbed up to my "fair safe go home altitude". 150'. The buildings on the water here are about 100'. But I was over the surf, and cancelled the command pretty quickly.

    I'll try replicating closer to me. My guess is that I won't succeed. But I guess I should see.

    As an aside, any spacial disorientation I've had was when trying to mix FPV with visual sight flying. If you are far away enough (Which isn't very far with this little thing in a bright sky) to need to fly solely by FPV and/or the map, DO THAT. Even if you're not supposed to. This is the same lesson I learned in light planes. If you are flying VFR and blunder into IFR conditions, DON'T play pretend, and look outside to "see and avoid other traffic" (You won't), while doing a rotten instrument flying job too. If you need to fly IFR and are not on a flight plan, it's bad but DO IT, get ATCs help, but don't play pretend and crash. Seems so obvious now. LOL

    Thanks everybody.
     
  10. phantom1972

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    I had never tried those functions. Wasn't sure I had the updated firmware -- I do. Then I remembered this reply. It sure does sound like somehow it may have slipped into that mode. Backing into the Geo Fence that I just happened to set, totally not being in mindset that I could have been in that mode, and being far away made me want to derails the problem ASAP. Which RTH did. I wish I had rotated 90 degrees, and pulled the stick towards me. That would have told the tale.

    Just an an aside, I think I verified something that I hoped would be the case. I posted it on another thread. The RTH button seems to have a reset that can clear out eroneous states. I've seen people struggling to figure out a problem, and when thee did pudgy RTH, they didn't have enough battery left. RTH could be used for its reset, its not a commitment.